Technical Field
This invention generally relates to an integrating sphere, more particularly to a structure thereof.
Related Art
An integrating sphere used in analysis of luminous flux of a light source or color of a measuring object is generally provided with a structure having a spherical inner wall (surface) wherein a light radiated from the light source repeats diffuse reflection on the spherical inner wall to be spatially-integrated, for example, as disclosed in Japanese Patent No. 4,272,629.
Specifically, in a conventional integrating sphere other than that disclosed in the reference, binders have been used to enhance release strength of a white coating material, as the release strength of the white coating material is significantly low in powder foam. Nevertheless, the release strength of the white coating material is still insufficient even using binders and what is worse, binders can be discolored by heat or ultraviolet light. Taking this into account, in the sphere disclosed in the reference, the spherical surface is configured to be coated, not with binders, but with a spraying membrane having a diffuse reflectivity for an incident light in the wavelength region to be used.